Denver's River North Brewery ranks as one of Colorado's best sour beer breweries. Photo: River North Brewery

Not every puckered face in Colorado is puffing on a joint — many of them are just reeling in the wonderfully tart-tastic aftermath of a sour beer, one of the buzzier trends sweeping the e’er-brewing-obsessed Centennial State.

Usually wild strains of yeast and bacteria are verboten in today’s hyper-hygienic, heavily patrolled breweries — they’re the illegal immigrants of the beer-making world. But more and more brewers are granting amnesty to these refugees, letting them run amok inside their sacred oak barrels. “Give me your tired, your poor, your Brettanomyces, Lactobacillus and Pediococcus,” they implore (of the wild yeast and two bacteria, respectively).

What results from these heavily aged beers is an acidic apocalypse in your mouth that’ll grab you by the ‘buds; it’s as if ICBMs carrying Sour Patch Kids were colliding with nuclear warheads filled with loads of, well, Warheads.

Here, the nine best Colorado breweries to visit on your next trip out West. Get your sour on — if you dare.

Mountain Sun (Denver)

Photo: Mountain Sun Pub & Brewery/FacebookThis Portland-inspired, Boulder-born brewery’s hometown operations don’t offer sour beer, but its Denver outfit — the Vine Street Pub & Brewery — is picking up the slack. Of its 62 oak barrels in the cellar, some are purely dedicated to making wild and sour beers to meet demand. They’re just getting ready to roll out Ciel Savauge Ale, a tweaked wild yeast-infused version of its Ciel Lumineux Pale Ale, which enjoys dual rounds of fermentation with the wildest of wild yeasts, Brettanomyces Drie Fonteinen.

Avery Brewing Company (Boulder)

Photo: Avery Brewing CompanyAvery’s got a mad genius of a barrel-ager by the name of Andy Parker, who’s become a celebrewer around town because of his Barrel-Aged Series, one-and-done creations sold in limited quantities.

At the Avery Tap Room, you can always find Eremita on tap (it’s not allowed to leave the house). Latin for “the Hermit,” it just might turn your tongue into a ‘fraidy cat recluse with its acidic bite. Eremita VII, its 7th incarnation, is a light-blonde sour aged in oak barrels for five months, then floratized with fresh-sliced cucumbers and whole-leaf hibiscus flowers.

Odell Brewing Company (Fort Collins)

Photo: Odell Brewing CompanyThe second-oldest microbrewery in Colorado has seamlessly jumped on the newest beer sensation — sink your fangs in its draft-only, tart barrel-aged black ale called Dr. Acula. If you vant to suck it down, it’s available exclusively at their tap room and a few local bars.

Otherwise, the only annual sour Odell has on offer is Friek, a Lambic-style Framboise/Kriek hybrid where cherry and raspberry flavors tag-team to tart up your life with a dry finish. In August, they’ll release Brazzle, a sour golden raspberry ale, and in 2015, their Piña Agria, a sour pineapple ale, will debut.

Pateros Creek (Fort Collins)

Photo: Pateros Creek Brewing Company/FacebookWhile its Stage Line Chili Porter, Sour Porter and ‘13 Apple Cinnamon Vanilla Dark Sour are in the past — RIP! — Pateros is all about living in the present, sour-heads. Its Rattlesnake Jack – Blackberry Chipotlé Ale — named for some bloke who used to throw rattlesnakes in the air before eating them (!) — is a 5.6 percent ABV venomous mix of blackberries, peanuts and chipotlé peppers; ssso sssour!

Pateros’ other sour option, Sandstone – Sour Red Ale, so called because of its reddish-brown hue (sandstone is to Colorado what pee-stained concrete is to NYC), is fermented with brett, lacto and pedio to create a tart, berry and plummy beer who’s happy ending is a roasted-malt surprise. We love surprises!

River North Brewery (Denver)

Photo: River North Oud BruinRiver North owners Matt and Jessica Hess are unapologetically yeastaholics and damn proud of it. They’re also strict advocates of the principle of slow and steady wins the race.

Their second bottle-conditioned release, Oud Bruin, is their reigning champion belt holder for Longest Beer To Make — it’s a Belgian-style sour brown ale that’s aged a good 20 months in red wine barrels with Brettanomyces. More like Brettano-NICE-ces, am I am right?

The creation of BrettBagger, a barrel-aged Brettanmyces Imperian White IPA, debuting July 29 — it’s something they collabed with Dragonmead and Kuhnhenn breweries to create. Did we mention it clocks in at 9.5 percent ABV? Extreme!!!!!

Our Mutual Friend Malt & Brew (Denver)

They have three sour ops to enhance said relationships: Wine Barrel Aged American Wild Ale (a collaboration with The Populist), Our Mutual Gose (gose is top-fermented German beer) and Barreled & Bretted Chinook Red Ale.

Crooked Stave Artisan Beer Project (Denver)

Photo: Crooked Stave Artisan Beer Project/FacebookNow squirreled away with a tasting room in the rear of The Source (a 15-tenant artisan food/bev warehouse in Denver’s River North District), these awesomely named folks were at the forefront of Colorado’s sour beer coup, brewing all of their creations with wild Brettanomyces, aging all in oak barrels under the aegis of “Founder and Brettanomyces Guru” Chad Yakobson, a k a Denver’s “Hipster Beer King.”

His royal highness never allows the place to offer less than five sours on tap (currently, they have nine!) — ATFs include its gaggle of Petite Sours (Blackberry, Blueberry, Passion Fruit and Pure Guava) and Nightmare on Brett.

New Belgium Brewing Company (Fort Collins)

Photo: New Belgium Brewing CompanyHands down, this author’s personal favorite sour is made at the granddaddy of craft breweries, the House that Fat Tire built, New Belgium. They have devoted 32 foeders — the wooden barrels used to age sours — to the ilk, and while Transatlantique Kriek and Le Terroir are both yums, La Folie (“The Folly,” en français) is the true Power Sour.

It’s a wood-aged, sour brown spending up to three years in those foeders — the law-schooler of sours. Warn your tongue ahead of time to expect a shrapnel-filled blast of Granny Smith apple, cherry pit, caramel and plum-skin flavors when you finally pull the pin on this 7 percent ABV, 22-ounced grenade.